The present invention relates to an ultrasonic Doppler blood flow measuring apparatus in which an ultrasonic wave is transmitted to and received from a subject to provide a reflected echo signal and a signal caused to undergo a Doppler shift by a blood flow is derived from the reflected echo signal to display blood flow information two-dimensionally and more particularly to an ultrasonic blood flow measuring apparatus capable of determining which of arterial and venous flows a blood flow in a region of interest belongs to and displaying arterial and venous flows in coloring fashion.
A conventional ultrasonic Doppler blood flow measuring apparatus of this type comprises, as shown in FIG. 5, a probe 1 for transmitting and receiving an ultrasonic wave to and from a subject, an ultrasonic wave transmitting/receiving circuit 2 for controlling the probe 1 so as to cause it to transmit and receive the ultrasonic wave and amplifying a received reflected wave signal, a Doppler demodulating circuit 3 for deriving a frequency signal, caused to undergo a Doppler shift by a blood flow in the subject, from the reflected echo signal produced from the ultrasonic wave transmitting/receiving circuit 2, a blood flow speed calculation circuit 4 for calculating a blood flow speed in the subject by using the frequency signal from the Doppler demodulating circuit 3, a blood flow speed frame memory unit 5 for storing blood flow speed information from the blood flow speed calculation circuit 4, a color signal conversion and display circuit 6 for receiving data from the blood flow speed frame memory unit 5 and converting it into a color signal complying with a blood flow state, and an image display 7 for receiving the color signal from the color signal conversion and display circuit 6 to perform a coloring display. An ultrasonic wave is transmitted from the probe 1 to a vessel of the region of interest in the subject, and a Doppler shift frequency of an ultrasonic wave reflected from red blood corpuscles in the vessel and received is measured to obtain blood flow information which in turn is displayed two-dimensionally on the image display 7.
In the conventional ultrasonic Doppler blood flow measuring apparatus as above, data from the blood flow speed frame memory unit 5 is inputted to the color signal conversion and display circuit 6 and converted into a color signal complying with a blood flow speed to ensure that for example, a blood flow approaching the probe 1 can be coloring-displayed in a color of red system and a blood flow departing from the probe 1 ca be coloring-displayed in a color of blue system but any display as to which of arterial and venous flows the displayed blood flow belongs to cannot be obtained. In other words, the difference of directions of the blood flow can be determined and displayed in coloring fashion but it is impossible to determine which of arterial and venous flows the blood flow belongs to and to display a determined arterial or venous flow discriminatively in coloring fashion.
Under the circumstances, in the event that a blood flow is interrupted for some abnormal causes in a region of interest where a great number of vessels run complicatedly, for example, in the liver or kidney, a doctor or the like sometimes is not permitted to execute correct diagnosis if he does not know which of arterial and venous flows the blood flow in question belongs to. In such an event, the doctor or the like is forced to execute diagnosis while considering which of arterial and venous flows the blood flow portion where abnormality is occurring belongs to on the basis of knowledge of anatomy. Accordingly, it takes a long time to execute diagnosis and efficiency is degraded. In addition, the doctor or the like sometimes arises the individual difference in diagnostic judgment and correct diagnosis cannot be done.